In a new study, scientists have discovered how dietary cocoa flavanols, the naturally occurring bioactives found in cocoa, reverse age-related memory decline in healthy older people.

The study led by Columbia University Medical Center (CUMC) scientists, provided the first direct evidence that one component of age-related memory decline in humans was caused by changes in a specific region of the brain and that such a form of memory decline could be improved by a dietary intervention.

Previous work had shown that changes in a specific part of the brain-the dentate gyrus-were associated with age-related memory decline. To see if the dentate gyrus was the source of age-related memory decline in humans, senior author Dr. Scott A. Small and his colleagues tested whether compounds called cocoa flavanols could improve the function of this brain region and improve memory. Flavanols extracted from cocoa beans had previously been found to improve neuronal connections in the dentate gyrus of mice.

In the CUMC study, 37 healthy volunteers, ages 50 to 69, were randomized to receive either a high-flavanol diet (900 mg of flavanols a day) or a low-flavanol diet (10 mg of flavanols a day) for three months. Brain imaging and memory tests were administered to each participant before and after the study. The brain imaging measured blood volume in the dentate gyrus, a measure of metabolism, and the memory test involved a 20-minute pattern-recognition exercise designed to evaluate a type of memory controlled by the dentate gyrus.

The high-flavanol group also performed significantly better on the memory test. Dr. Small said that if a participant had the memory of a typical 60-year-old at the beginning of the study, after three months that person on average had the memory of a typical 30- or 40-year-old. He cautioned, however, that the findings needed to be replicated in a larger study.

Flavanols are also found naturally in tea leaves and in certain fruits and vegetables, but the overall amounts, as well as the specific forms and mixtures, vary widely.

The precise formulation used in the CUMC study had also been shown to improve cardiovascular health. Brigham and Women's Hospital in Boston recently launched an NIH-funded study of 18,000 men and women to see whether flavanols can help prevent heart attacks and strokes.

The researchers pointed out that the product used in the study is not the same as chocolate, and they caution against an increase in chocolate consumption in an attempt to gain this effect.

In the study, the researchers were unable to assess whether exercise had an effect on memory or on dentate gyrus activity.

The study is published in the advance online issue of Nature Neuroscience.